A simple conductimetric method as an alternative to the colorimetric p-nitrobenzylpyridine test for the measurement of the reactivity of potentially mutagenic alkylating compounds.

A simple method for the measurement of the kinetics of reaction of potentially mutagenic alkyl halides with amines, based on the direct conductimetric monitoring of the quaternary ammonium salt produced in these reactions, is proposed and applied to the alkylation of p-nitrobenzylpyridine (NBP) and triethylamine (TEA) in different solvents. With respect to the classical colorimetric NBP-test, this method has the advantage that the rates can be measured continuously over the entire course of the reactions and the kinetic order and constants can be easily obtained. It is also shown that the previously proposed, NBP modified test', using simultaneously NBP and TEA, gives actually the sum of the rate constants for the reactions of the alkylating reagent with the two amines.